The present invention relates to a silver salt photo-thermal photographic dry imaging material excellent in the high density, the light fastness of image and the tone of silver image, an image recording method and an image forming method employing that. Hitherto, in the field of the medical and the plate making for printing, exhausted waste liquid accompanied with the wet treatment causes problems from the viewpoint of the working efficiency. Recently, the reduction of the exhausted waste liquid is strongly demanded also from the viewpoints of the environment protection and the space saving. Consequently, the silver salt photo-thermal photographic dry imaging material capable of forming an image only by heating is made practicable and rapidly spread in the above fields.
The silver salt photo-thermal photographic dry imaging material, hereinafter referred to as thermally developable material or simply as light-sensitive material, is previously proposed such as that described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075.
The thermally developable material is usually treated by a developing apparatus so called as a thermal developing apparatus which gives stable heating to the thermally developable material to form an image. A lot of such the heat developing apparatus has been supplied to the market accompanied with the rapidly spreading of the thermally developable material as above-mentioned.
There is a problem, however, that the fault of conveyance of the thermally developable material and the unevenness of the image density are caused by the changing of the slipping property between the thermally developable material and the conveying roller or the processing member depending on the environment such as temperature and humidity. Furthermore, it has been the problem that density of the silver image is changed during the storage for a prolonged period. It is found that these phenomena considerably occur in the thermally developable material for forming an image by thermal development after the imagewise exposure by laser light.
Recently, the miniaturization of the laser imager and the speed up of the treatment are demanded. For obtaining sufficient image density by the thermally developable material, even when developed by speedy treatment, it has been proposed to raise the covering power by employing silver halide having a small average particle size, to use a high reactive reducing agent such as a compound having a secondary or tertiary alkyl group, and to use a development accelerating agent such as phenol compounds, hydrazine compounds and vinyl compounds described in, for example, Japanese Patent Publication Open to Public Inspection, hereinafter referred to as Japanese Patent O.P.I. Publication, Nos. 11-295844 and 11-352627.
However, when the silver halide particles having the small average size are simply used for raising the covering power, the stability of the dispersion of the silver halide particles is conversely lowered and the transparency of the image is degraded, and degradation of the haze in the low density area is resulted. Moreover, problems rise when these techniques are applied that the variation of the density or printout during the storage for prolonged period is increased and the tone of the silver image is largely become different, for example made yellowish, from that of the image obtained by the usual light-sensitive material to be developed by the wet processing. Moreover, a problem is newly found that the tone at the high density area having a density of not less than 2.0 of the image is made reddish when the silver halide particles having the small average size are employed.
As the countermeasures to such the problems, for example, Japanese Patent O.P.I. Publication Nos. 11-288057, 11-231460 and 2001-264926 disclose techniques to control the tone of silver image by employing couplers or leuco dyes. In any method, however, the desired tone control can not be attained since the fog is raised during the storage for a prolonged period when the amount of the coupler or the leuco dye is increased.